Expression of genes encoding neuropeptides and enzymes in the brain, with emphasis on the hypothalamus, are being studied. We successfully created a "knock-out" of the oxytocin gene in mice through homologous recombination. These mice demonstrate that oxytocin is absolutely required for milk ejection, but not mammary gland development, fertility or parturition. We are conducting further studies to see how the absence of oxytocin affects mouse behavior and reproduction. Initial studies indicate that some aspects of aggressive behavior are decreased. This year, we also generated knock-outs of the oxytocin receptor. The phenotypes of these mutant mice are currently undergoing intense study. We extended our studies of the novel POU protein, RHS2 (Brain-4), whose full-length cDNA we previously cloned. We mapped the sites of expression, including during development in the mouse, of the four class III POU proteins to further our understanding of their roles. We also determined that the class III proteins interact with each other in far-western and two-hybrid assays. We determined that Brain-4 interacts with a nuclear protein that may be involved in RNA processing. We used the technique of differential display to isolate the genes from pineal gland. One novel gene, PG10.2, was also found expressed in the retina of rats and humans. We determined its chromosomal location and we are trying to determine if it is linked with any human retinal diseases. Mapping of gene expression in the human hypothalamus continues: analyses of vasopressin, oxytocin, LHRH, substance P, neurokinin B and the opioids have been published. Maps of the corticotropin-releasing factor, somatostatin, and growth hormone-releasing factor are in progress.